1. Field of the Invention
The present invention relates to a heat-dissipating fan. In particular, the present invention relates to a heat-dissipating fan used in computers or electronic equipment, the heat-dissipating fan having a single stator located outside the fan wheel.
2. Description of the Related Art
It is common to use a heat-dissipating fan in a computer or electronic equipment. FIG. 1 of the drawings illustrates a conventional heat-dissipating fan 1, in which a stator 10 is placed in a middle portion of an interior space of a fan wheel 12, and fan blades 14 are provided on an outer periphery of the fan wheel 12. The heat-dissipating fan 1 is coupled to a fin unit 2 for dissipating heat generated by a heat-generating element 3 such as a central processing unit. In operation, the stator 10 and the fan wheel 12 occupies most part of a central portion of the fin unit 2 such that no wind could enter this part. However, the heat generated by the heat-generating element 3 concentrates in the central portion of the fin unit 2 (see the circled portion A). As a result, the air output by the heat-dissipating fan 1 could not match the heat distribution. Namely, no wind is provided for the hottest central portion, and a large amount of air is provided for the remaining area having a lower temperature. The cooling effect is poor, and a considerable amount of energy is required if it is desired to cool the heat-generating element 3 to the desired extent.
FIG. 2 illustrates another conventional heat-dissipating fan 4 designed for eliminating the drawback of the heat-dissipating fan 1 in FIG. 1. The heat-dissipating fan 4 includes a ring magnet 40 mounted around the fan blades 42, and four single-poled stators 44 are mounted around the ring magnet 40 and spaced at regular intervals. The wind output problem of the heat-dissipating fan 1 in FIG. 1 is solved. Further, the effective diameter of the fan blades 42 is increased, which increases not only the amount of air output but also the area of air output. A better heat-dissipating effect is provided. However, the four single-poled stators 44 are close to one another, resulting in difficult fixing of the stators 44 and difficult connection between the coils of the stators 44. The overall weight of the heat-dissipating fan 4 is increased. Further, since the core of each it single-poled stator 44 lacks a direct loop for the magnetic field, the electromagnetic power loss is large and the efficiency is poor.
It is the primary object of the present invention to provide a heat-dissipating fan for eliminating the above-mentioned drawbacks. The heat-dissipating fan in accordance with the present invention provides the advantages of: increasing the amount of air output, improving the heat-dissipating efficiency, reducing the overall weight, reducing the manufacture difficulty, reducing the manufacture cost, having a small electromagnetic power loss, and having a high efficiency.
A heat-dissipating fan in accordance with the present invention comprises a rotor and a stator. The rotor includes a ring magnetic mounted to an outer periphery thereof. The stator includes a core. A plurality of poles integrally extend from the core of the stator. An induction coil is wound around at least one of the poles and located on an end of the pole.
In an embodiment of the invention, there are two poles integrally extending from the core of the stator, providing a U-shaped structure for said core.
Other objects, specific advantages, and novel features of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings.